Method for interchanging curvature of cathode-ray tube face plate



Sept. 5, 1967 r H. KASPEROWICZ ET AL METHOD FOR INTERCHANGING CURVATURE OF CATHODE-RAY TUBE FACE PLATE Filed Oct. 28, 1964 & JK

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HEMP Ay mwwcz INVEZTO RS 7 Y Maw/1a gas /wk ATTORNEY United States Patent 3,340,032 METHOD FOR INTERCHANGING CURVATURE OF CATHODE-RAY TUBE FACE PLATE Henry Kasperowicz, Clifton, and Michael Gasparik, Ridgewood, N..I., assignors to General Electronics Corporation, Newark, N.J., a corporation of New Jersey Filed Oct. 28, 1964, Ser. No. 407,031 4 Claims. (Cl. 6537) This invention relates in general to methods of interchanging the internal face plate curvatures of cathoderay tubes and is particularly directed to simply and economically changing the spherical curvature of the face plate panel in a television picture tube to a toroidal type curvature; wherein, for example, the minor axis of the internal face plate surface has a relatively large radius of curvature in comparison to the major axis.

All commercially available television picture tubes have face plate panels whose interval surfaces are spherical or substantially spherical in curvature. These tubes are considerably less expensive than those tubes whose surfaces have a special curvature, e.g., toroidal, cylindrical and etc. The production volume of such tubes is presently nonexistent and tubes designed with such surfaces are very expensive and commercially-impossible to produce economioally because of the prohibitive costs in tooling and manufacturing and limited sales volume. To permit the use of such commercially available tubes in the area where the tubes having other type curvatures are useful and necessary, a special insert has been provided herein which is produced and mounted in a novel manner and thus forms the basis of the invention.

In particular type of color tube, such as that generally known as the chromatron picture tube, invented by E. O. Lawrenge, US. Patent No. 2,692,532, the curvature of the face plate panel has a toroidal type configuration, the radius of curvature along the major axis being smaller than the curvature along the minor axis. This curvature arrangement is necessary because of the electron-optic and beam convergence dynamics peculiar to the chronitron. To produce glass bulbs having this face plate curvature is quite expensive and makes the cost of the overall receivers prohibitive.

It is therefore a principal object of the invention to provide a method of converting the face plate panel curvature of commercially available tubes to curvatures of tubes not commercially available.

Another object of the invention is to provide a method of producing television picture tubes which is simple, efiicient and economical.

Another object of the invention is to provide a method of converting television picture tubes of one picture surface configuration to television picture tubes of another picture surface configuration which is simple, quick and inexpensive.

Other objects and advantages will become apparent from a reading of the specifications and a study of the accompanying drawings and wherein;

FIGURES 1 and 2 show pictorially and in section a picture television tube of the post-deflection-focusing type such as the chromatron.

FIGURES 3 and 4 show molding means and a glass insert prior to compression or molding into the desired shape.

FIGURE 5 shows the formed insert having the desired curvatures on the opposing surfaces thereof.

FIGURES 6 and 7 show a commercially available television bulb face plate panel and the insertion of the glass insert which produces a chromatron type configuration.

Now proceeding to describe the invention with respect to the various figures, there is shown particularly in FIG- URES 1 and 2 a television picture tube classified as a 3,340,032 Patented Sept. 5, 1967 ice post-defiection-focusing type, e.g., the chromatron, and comprising a glass bulb 10 with a glass face plate panel 11 forming a part thereof. An indirectly heated cathode 12 acts as a source of electrons for development into a scanning beam, the latter being indicated by the trace 13. Adjacent to and partially surrounding the cathode 12 is a control grid 14, suitably apertured to permit the passage of electrons in accordance with the potentials applied thereto relative to the' cathode 12. Also within the tube there is provided a first anode 15 to which suitable potentials may be applied so as to result in an initial acceleration of electrons emitted from the cathode 12. Adjacent to anode 15 there is positioned a second anode 16 for applying an additional acceleration to the electrons. Defiection coil 17 for the usual vertical and scanning purposes are provided together with focusing coil 17a to cause the electron beam to scan a phosphor coated target 18, to produce light which is visible through the face plate panel 11 of the cathode-ray tube 10. A switching grid 20, usual to the above mentioned chromatron tube is shown suitably positioned within the tube 10 so as to cause the beam 13 to intercept the target at the appropriate point. All of the above is by way of illustration to show how this particular tube is constructed and used and why the electron-optics and convergence dynamics dictate this tube and the curvature thereof at the viewing area.

To convert the commercially available bulbs to the type indicated here by way of illustration (chromatron) it is necessary to first produce an insert having the desired surface configuration to match both tube surfaces. This may be accomplished, as shown in FIGURES 3 and 4, 'by first inserting a substantially flat rectangular glass plate 30 between a pair of molds 31 and 32, each having the pressure surfaces 33 and 34 suitably curved to match the new converted tube and the commercial tube, respectively. The molds 31 and 32 are both or singly placed in compression, the insert between them undergoing compression accordingly to take on the mold curvatures. The glass insert, prior to mold compression, is preferably and suitably heated, the temperature thereof raised to a level to make it pliable and moldable when undergoing compression in the mold to assure its ability to take on the above mentioned curvature. It is also possible to elevate the insert temperature to a degree so that when placed on the lower mold part 32, the insert will sag and take on substantially the surface configuration of the said mold. The upper mold part 31 is then merely placed in compression upon the insert to'form an impression thereon equal to the other surface configuration.

In a particular embodiment and/or application the mold portions 31 and 32 each have, respectively, toroidal and spherical curvature configurations. In FIGURE 3, the major axis of the mold 31 has a substantial cylindrical curvature, the radius of curvature being relatively small as compared to the radius of curvature of the minor axis, as shown in FIGURE 4, taken along the line 4-4 of FIGURE 3. The mold part 32 has a spherical radius of curvature, and the said radius is equal along both the major and minor axis. The glass insert 30, when shaped according to the above outlined procedure appears as shown in FIGURE 5, wherein one surface 35 has a convex spherical configuration and the opposing surface 36 has a concave toroidal configuration.

The shaped insert 30 is then mounted to a commercially available face plate panel 40 as shown in FIGURES 6 and 7. In particular, the insert 30 is placed within the panel so that the spherical surface of both members are of the insert with the glass panel permits the major and minor axis of the glass insert surface, opposite the spherical side, to look like a chromatron or torroidal-shaped surface. The electron beam thus approaches this toroidal surface and the tube in all its electron-optic aspects behaves as a chromatron.

Having defined the invention what is claimed is:

1. A method of converting the face plate inner surface curvature of a television picture tube comprising:

(a) preparing a mold member composed of dual opposing compressive parts, one having a surface curvature matching the tube inner surface and the other having a surface curvature matching the new tube,

(b) placing a flat glass plate between the mold parts,

() heating the glass plate to a temperature to cause it to become pliable,

(d) compressing the mold parts upon the glass plate to cause it to conform to the surface configuration of the mold parts,

(e) allowing the formed glass insert to cool to become structurally rigid, and

(f) inserting and adhering the glass plate to the television picture tube to form a television tube having a new surface configuration.

2. A method of converting the face plate panel inner surface curvature of a television picture tube comprising;

(a) preparing a metal mold member composed of dual opposing compressive parts, one having a surface curvature matching the tube inner surface and the other having a surface curvature matching the new tube,

(b) placing a flat glass plate between the mold parts,

(c) heating the glass plate to a temperature to cause it to become pliable,

(d) compressing the mold parts upon the glass plate to cause it to conform to the surface configuration of the mold parts,

(e) allowing the formed glass insert to cool to become structurally rigid,

(f) placing the glass insert within the television picture tube face plate panel, and

(g) applying glass frit along the periphery of said insert and causing it to solidify to produce a firm bond between insert and face plate panel to form a television tube having a new surface configuration.

3. A method of converting the face plate panel inner surface curvature of a television picture tube comprising;

(a) preparing a metal mold member composed of dual opposing compressive parts, one having a surface curvature matching the tube inner surface and the 4 other having a surface curvature matching the new tube,

(b) placing a flat glass plate between the mold parts,

(c) heating the glass plate to a temperature range of between 400 to 600 degrees Fahrenheit to cause it to become pliable,

(d) compressing the mold parts upon the glass plate to cause it to conform to the surface configuration of the mold parts,

(e) allowing the formed glass insert to cool to ambient temperature to become structurally rigid,

(f) placing the glass insert within the television picture tube face plate panel, and

(g) applying low temperature glass solder along the periphery of said insert and causing it to solidify to produce a firm bond between insert and face plate panel to form a television tube having a new surface configuration.

4. A method of converting the face plate inner surface spherical curvature of a television picture tube comprising;

(a) preparing a metal mold member composed of dual opposing compressive parts, one having a spherical surface curvature matching the tube inner surface and the other having a toroidal surface curvature matching the new tube, the said toroidal surface having a relatively large radius of curvature along its minor axis as compared to the radius of curvature along the major axis,

(b) placing a fiat glass plate between the mold parts,

(c) heating the glass plate to a temperature to cause it to become pliable,

(d) compressing the mold parts upon the glass plate to cause it to conform to the spherical and toroidal surface configuration of the mold parts,

(e) allowing the formed glass insert to cool to become structurally rigid, and

(f) inserting and adhering the glass plate to the television picture tube to form a television tube having a new toroidal surface configuration.

References Cited UNITED STATES PATENTS 2,339,975 1/1944 Blau 65106 X 2,382,660 8/1945 Penberthy 6537 X 2,817,928 12/1957 Lambert et al 65l06 2,890,486 6/1959 Crandon 249134 S. LEON BASHORE, Acting Primary Examiner.

A. D. KELLOGG, Assistant Examiner. 

1. A METHOD OF CONVERTING THE FACE PLATE INNER SURFACE CURVATURE OF A TELEVISION PICTURE TUBE COMPRISING: (A) PREPARING A MOLD MEMBER COMPOSED OF DUAL OPPOSING COMPRESSIVE PARTS, ONE HAVING A SURFACE CURVATURE MATCHING THE TUBE INNER SURFACE AND THE OTHER HAVING A SURFACE CURVATURE MATCHING THE NEW TUBE, (B) PLACING A FLAT GLASS PLATE BETWEEN THE MOLD PARTS, (C) HEATING THE GLASS PLATE TO A TEMPERATURE TO CAUSE IT TO BECOME PLIABLE, (D) COMPRESSING THE MOLD PARTS UPON THE GLASS PLATE TO CAUSE IT TO CONFORM TO THE SURFACE CONFIGURATION OF THE MOLD PARTS, (E) ALLOWING THE FORMED GLASS INSERT TO COOL TO BECOME STRUCTURALLY RIGID, AND (F) INSERTING AND ADHERING THE GLASS PLATE TO THE TELEVISION PICTURE TUBE TO FORM A TELEVISION TUBE BEING A NEW SURFACE CONFIGURATION. 